In any clay deposit, the
nature of the mineral assemblage and the composition of individual clay
minerals can change radically in a few centimeters.Consequently, any given locality can contain many subtly
different types of clay minerals. Results from different laboratories on
ostensible the same clay mineral may not always be comparable because the
samples may indeed not contain the same clay mineral.Such confusion slows the understanding of this important group of
minerals.

Earlier
collections

The
first major effort to correct the situation probably was American Petroleum
Institute Project 49, under the direction of Paul F. Kerr at Columbia University
in the 1940s.The goal was to collect
samples of representative clays, analyze them, and publish the results.Ralph Holmes collected materials from a
large number of localities.The data
appeared in an impressive volume (API Project 49), well known to earlier
practitioners in the field. API made samples of the materials available, and
later Wards Natural Science Establishment assumed responsibility in selling
them. As in any pioneering project, some problems eventually appeared.The effort did not attempt to homogenize
each material.Heterogeneity became
evident.Eventually, supplies of the
most popular materials ran out.Nevertheless, this effort proved immensely valuable in furthering clay
mineral research.

CMS
project development

The
Clay Minerals Society involvement began in 1969, when Robert W. Rex proposed a
“Reference Clay Mineral” bank to be under the auspices of the Society.Shortly thereafter, other commitments
occupied his time and the project did not proceed.In 1970, George Brindley, who supported the idea, approached
William Moll at Georgia Kaolin Company to champion it.

Brindley
and Moll considered several approaches to collect, house, and distribute such a
collection. They first considered the National Bureau of Standards, which they
visited in January 1971.They decided
that the NBS would not be appropriate, in part because the Society would loose
control of the collection.Moll then
visited William D. Johns at the University of Missouri-Columbia in March
1971.Johns was interested in having
the collection at Missouri.The
University and the Geology Department was enthusiastic, and would develop a
proposal. The University of Missouri-Columbia was particularly attractive
because it had two eminent clay mineralogists, Bill Johns, and Walter Keller,
as well as C.E. Marshall who also worked in clays.Further, because of the economic importance of clay mining in
Missouri, all involved believed that the Geology Department would always have a
strong interest in clays.

Moll
then gave a report regarding the proposed “Reference Clays” project at the CMS
Council meeting in Rapid City, South Dakota, in August 1971.The Council set up an ad hoc committee to pursue establishing such a repository.By early 1972, Johns and the University had
developed a plan. The University agreed
to provide space and facilities for storage and its accounting department to
handle the billing. William D. Johns volunteered to serve as curator. The
start-up costs, including containers, equipment, and a graduate student as a
part-time clerk, would be $4000.

In
May 1972, H. van Olphen and Moll presented the Missouri proposal to CMS Executive
Committee meeting in Washington, DC.The
Executive Committee tentatively approved it, and sent out a mail ballot to
the CMS Council. After final approval by the Council, preparations began.
At the Society meeting in Woods Hole, MA, in September 1972, several
industrial firms agreed to provide the samples.Participating at this time were Lin Haden of
Engelhard Corporation, John (“Spike”) Jordan of Baroid Division-National Lead
Company, and Haydn Murray of Georgia Kaolin.Jordan offered the use of the Baroid pilot plant to process the material.

Collection
and processing

The
firms had professional geologists carefully collect and document each
sample.Note that these industrial
firms invested a great deal of time and money in collecting, processing, and
delivering the materials for the Society.

Sample

Donated by

Collection location
Collection supervision

Collection date

Kaolin

KGa-1

KGa-2

Georgia Kaolin Co.

KGa-1: 17 km west of
Sandersville, GA;

KGa-2: 14 km north of
Wrens, GA

John Smith

4 Oct 1972

(for both)

Wyoming bentonite

SWy-1

Baroid Division-

National Lead Co.

50 km west of Colony, WY Richards
Rowland

3 Oct. 1972

Texas white bentonite

STx-1

Southern Clay Products Co.

10 km east of Gonzales, TX

David Christian

late1972

Cheto montmorillonite

SAz-1

Filtrol Corp.

10 km ESE of Sanders, AZ

Robert Secor, Robert
Schwenkmeyer

late 1972

Hectorite

SHCa-1

Baroid Division-

National Lead Co.

5 km south of Hector, CA.

A.J. Higgins

Nov. 1972

Attapulgite

PFl-1

Engelhard Corp.

Gadsden County, FL

Jack Wilkinson

13 Oct. 1972

Synthetic Mica-montmorilloniteSyn-1

Baroid Division-

National Lead Co.

Wallisville, TX, plant
William T. Grandquist

late 1972

Each
raw sample would provide one metric ton of processed material.The decision was made to homogenize the
samples. Of course some things would be lost in the homogenization process,
such as the fabric of the clay.Nevertheless, more would be gained by having a large number of units of
reasonably identical materials. The processing was minimal. It included drying
on steam-fired tray dryers at no greater than 100° C. Heaping into a pile, and
quartering ensured an even feed into the pilot plant Raymond roller mill used
for pulverization. Storage of the pulverized material was in large polyethylene
bags places in paperboard drums.The
Baroid pilot plant in Houston, under the capable direction of the very
experienced Harry Stuchell processed all but one of the original samples.The Southern Clay Products plant in
Gonzales, Texas, processed the Texas white montmorillonite, using a rotary
dryer and Raymond roller mill, under the direction of David Christian.

Name

The
name selected for the program was “Source Clay Minerals,” to preclude the idea
that a “standard” montmorillonite, for example, exists.In 1973, the program expanded to include
other types of clays not amenable to homogenization.The first materials were rectorite and cookeite supplied by the
Arkansas Geological Commission.These
materials became the “Special Clays.”

Coding
system

The
coding system resulted from a request in 1973 by F. J. Flanagan at the U.S.G.S.
(1974). He was preparing a compendium of research materials for the earth
sciences that would include such codes.The code included a letter for the mineral type, a letter for the
locality, and a sequential number. Following this procedure, the Cheto
montmorillonite code, for example, became SAz-1, signifying the first smectite
sample from Arizona.

Project
underway

By
early 1973, all the materials had reached the University, and the program was
underway. A paper presented by Moll, Johns, and van Olphen at the 1975
International Clay Conference in Mexico City described the program to an
international audience.Van Olphen and
Fripiat included the materials in their “Data Handbook for Clay Minerals and
other Non-Metallic Minerals” (Pergamon, 1979). This volume gave detailed descriptions of the collection
localities, as well as analytical data on the samples.

Replenishing

Inevitably,
even a metric ton proved insufficient for the very popular materials such as SWy-1
Wyoming montmorillonite, and KGa-1 low defect (formerly “well crystallized”)
kaolinite. Documentation of the original collecting sites was sufficient to
enable collecting additional materials of similar characteristics.

Sample

Donated by

Collection location Collection supervision

Collection date

Wyoming bentonite

SWy-2, the replacementforSWy-1

American Colloid Co.

Adjacent to locality of SWy-1I.E. Odom

June 1993

Kaolin KGa-1b, the
replacement for KGa-1

Engelhard Corporation

3 km SW of collection site
of KGa-1

Robert Pruett, H.L. Webb

22 Jan. 1993

Unfortunately,
the Baroid pilot plant had closed by this time.For the Wyoming bentonite, American Colloid used a rotary dryer
and a Raymond roller mill, with processing suggested by I. E. Odom. For the
kaolin, A. P. Green Refractories used a blower oven for drying and a hammer
mill for pulverizing, under the direction of Charles Stack.

Continuation
of the program

The
program has enjoyed continual improvements over the years by adding new samples
to the collection.Recent years have
seen increased public interest in safety and health. To address this interest,
the Society prepared Material Safety Data Sheets for each of the materials in
the repository.

Johns
and Keller retired from the University of Missouri-Columbia in the late 1990’s,
and the Geology Department showed declining interest in clay mineralogy.In 2001, the Department announced it would
like a new arrangement.Jessica Kogel,
president of the Society, Candice Johns, chair of the Source Clays committee,
and Bill Johns, curator, decided moving the collection to a different location
was best.They and the Society considered
several options, and decided to accept the offer of Cliff Johnston at Purdue
University.The collection was moved to
Purdue in August 2002.

Large
numbers of people, institutions, and companies have given time and effort to
make the project a success.William D.
Johns deserves much of the credit for managing the repository in his position
as curator for so many years.Moll
continued to chair the committee until 1981, when James Post assumed the
position.He was able to expand the
offerings greatly.Later Jessica Elzea Kogel
and now Candice Johns have served as effective chairs.